C_str的入门级notes

#include <stdio.h>
#include <string.h>
int main() {
    char str[] = "sstr";
    // "sstr." == ‘s‘, ‘s‘, ‘t‘, ‘r‘, ‘\0‘
    // without a ‘\0‘ it‘s usually not considered a c-style string
    // but a normal array of type char
    // many lib funcs need ‘\0‘ to identify a complete string

    printf("%s\n", sstr);
    scanf("%s", sstr);  // stops reading when meets a space
    printf("\n%s\n", sstr);
    gets(str);  // reads a full line until a ‘\n‘ 
                // (‘\n‘ not included)
                // puts(char[]) is less used, automatically ‘\n‘
    int len = strlen(sstr);  // ‘\0‘ not included
    // strcat(aimStr, sourceStr);  // 2 ‘\0‘ needed and 1 remains
    // strcat(aimStr, sourceStr, n); // only n bytes
    // strcpy(aimStr, sourceStr (, n));
    // strcmp(strA, strB (, n)); // strA-strB  (the first n bits)
                        // ascii bigger, string bigger
                        // the longer, the bigger
    // strlwr(sstr); strupr(sstr);
    newStr = strstr(char* text, char* match);
    // char* arrayAddress = strrev(sstr);
    // strset etc, recommeding memset(void* _Dst, int _Val, size_t _Size);
                            // mem.h or string.h
    double doublePrecision = strtod(strFloat, &endptr);
    // atoi，atol，strtod，strtol，strtoul
    // proto: longstrtol(char *str, char **endptr, int base);



    // for io
    c = getchar();  // dangerous, ‘\n‘ and all asciis untouched
    gets(sstr);  // ‘\n‘ is read and replaced by ‘\0‘
    scanf(... , someStr)  // buf still holds ‘\n‘, ‘ ‘, etc
    scanf(... , &someChar)  // close to getchar()
    // for formatted io, related sources:
    // http://www.jb51.net/article/62358.htm
    // http://baike.baidu.com/link?url=Ijwdh1w3qXfTtff-WlPW1QowBiaCgE7zjVHAOT35VHDXtmz3MmQhPk7zs-_pc1_7rI9-AZRZr60hWlgzPeUzQa
    // focus:  operator precedence
    // file io is important but not in the range
}